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ABSTRACT
Building heating is the main type of heating consumption in China. At present, there is a lack of attention given to the assessment of ecological cost or impact considering energy depreciation for various heating schemes. In this work, a method of exergy-ecology assessment is proposed to evaluate the energy and ecological characteristics of four basic building heating schemes. The solar-equivalent joule was adopted as the unified quantitative value of ecological impact by converting exergy, material, and cost flows. The exergy-ecology balance was established for each scheme, and a series of indexes were proposed and calculated through two strategies. The results show that the objective exergy efficiency of Scheme 3 heat pump is the highest (53.87%) and that of Scheme 2 electric heater is the lowest (17.58%). Larger difference of energy grade between energy providing side (0.83 for gas fuel and 1 for electricity) and receiving side (0.18 for output water) connects with lower exergy efficiency. Scheme 3 heat pump has the highest eco-exergy efficiency under both assessment strategies (71.89% and 53.86%), followed by Schemes 4 solar collector (61.52% and 36.34%). This method proves that the thermodynamics perfectness of system is positively correlated with ecological sustainability and can be used to assess other energy systems.
Nomenclature
| Q | = | Input heat or solar energy |
| W | = | Input work or electricity |
| H | = | Enthalpy |
| ΔU | = | Change of the internal energy |
| = | Energy efficiency | |
| E | = | Exergy |
| I | = | Exergy loss |
| α | = | Material grade |
| A | = | Process grade |
| S | = | Eco-exergy flow |
| C | = | Cost flow |
| B | = | Eco-exergy value |
| β | = | Ecological impact |
| Subscripts | = | |
| in | = | Input |
| out | = | Output |
| T | = | Temperature |
| p | = | Pressure |
| x | = | Composition |
| p | = | Product |
| int | = | Internal |
| ext | = | External |
| gen | = | General |
| obj | = | Objective |
| c | = | Cost flow over the life cycle |
| om | = | Operation and maintenance |
| d | = | Disposal process |
| mp | = | Eco-exergy flow of material |
| ep | = | Eco-exergy flow of energy |
| eco | = | Eco-exergy |
| pay | = | Payment |
| gain | = | Gain |
Disclosure statement
No potential conflict of interest was reported by the author(s).
Credit author statement
Haoxiang Duan: Methodology, Writing-review, Modeling, Project administration. Xiaohui Chen: Investigation, Draft preparation, Software. Qin Liu: Methodology, Draft preparation. Yun Li: Writing-review & editing. Jie Zhang: Project administration. Weijia Huang: Data curation, Conceptualization.
Additional information
Funding
Notes on contributors
Haoxiang Duan
Haoxiang Duan is currently pursuing a third-year master’s degree at the School of Energy and Power Engineering at University of Shanghai for Science and Technology and has been receiving education since 2021. His research interests are energy conversion system, exergy analysis, and carbon neutrality.
Xiaohui Chen
Xiaohui Chen is an Associate Research Fellow at Guangdong Science and Technology Infrastructure Center, Guangdong, China. He received his Ph.D. from Beijing University of Chemical Technology, China in 2015. His research interests are energy conversion and chemical process, energy saving and carbon neutrality.
Qin Liu
Qin Liu is currently pursuing a third-year master’s degree at the School of Energy and Power Engineering at University of Shanghai for Science and Technology and has been receiving education since 2022. Her research interests are oriented to exergy analysis of energy system; CO2 capture absorbents, and chemical affinity.
Yun Li
Yun Li is an Associate Professor at the University of Shanghai for Science and Technology. She holds a PhD in Chemical Engineering and Technology from Beijing University of Chemical Technology. Her publications are oriented to CO2 capture, utilization and storage and thermodynamic properties of working fluids.
Jie Zhang
Jie Zhang has been with the School of Energy and Power Engineering at University of Shanghai for Science and Technology since 2018, after earning his Ph.D. and serving as a postdoc at East China University of Science and Technology (2016-2018). His research interests include heterogeneous catalysis, CO2/H2O/H2 utilization, chemical process design, and evaluation of energy efficiency for utilization of carbonaceous materials.
Weijia Huang
Weijia Huang is an Associate Professor at the University of Shanghai for Science and Technology. He holds a PhD in Chemical Engineering and Technology from Beijing University of Chemical Technology. His publications are oriented to exergy analysis of complex fuels and energy systems; CO2 capture, utilization and storage; and thermodynamic properties of working fluids.